Iodide management in formamidinium-lead-halide–based perovskite layers for efficient solar cells

Healing defects with triiodide ions Deep-level defects in organic-inorganic perovskites decrease the performance of solar cells through unproductive recombination of charge carriers. Yang et al. show that introducing additional triiodide ions during the formation of layers of formamidinium lead iodide, which also contain small amounts of methylammonium lead bromide, suppresses the formation of deep-level defects. This process boosts the certified efficiency of 1-cm 2 solar cells to almost 20%. Science , this issue p. 1376